JP2006106610A - Process cartridge and electrophotographic image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a process cartridge capable of making smooth the transmission of a driving force from an electrophotographic photoreceptor to a transfer roller on an electrophotographic image forming apparatus main body side. <P>SOLUTION: The process cartridge D, which comprises a main body driving means 131, a transfer roller 104 for transferring a developed image to a recording medium, and a transfer roller pulley 160 for driving the transfer roller, and is detachably loaded in the electrophotographic image forming apparatus main body C forming an image on the recording medium, has the electrophotographic photoreceptor 107, a developing means 122 of developing a latent image formed on the electrophotographic photoreceptor with a developer, a driving reception portion 107a1 which is coupled to the main body driving means to transmit a driving force to the electrophotographic photoreceptor, and a photoreceptor pulley 107a which is driven with the driving force that the electrophotographic photoreceptor receives from the driving reception portion, and a driving transmission belt 155 which engages the photoreceptor pulley. When the process cartridge is loaded in the apparatus main body, the driving transmission belt engages with the photoreceptor pulley to increase the angle of winding between the photoreceptor pulley and driving transmission belt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a process cartridge and an electrophotographic image forming apparatus to which the process cartridge can be attached and detached.

  Here, the electrophotographic image forming apparatus forms an image on a recording medium using an electrophotographic image forming process. For example, an electrophotographic copying machine, an electrophotographic printer (for example, an LED printer, a laser beam printer, etc.) , An electrophotographic facsimile machine, an electrophotographic word processor, and the like.

  Conventionally, in an electrophotographic image forming apparatus for forming an image on a recording medium using an electrophotographic image forming process, the electrophotographic photosensitive member and the process means acting on the electrophotographic photosensitive member are integrally formed into a cartridge, and the cartridge Is a process cartridge system that can be attached to and detached from the main body of the electrophotographic image forming apparatus. According to this cartridge system, the maintenance of the apparatus can be performed by the user himself / herself without depending on the service person, so that the operability can be remarkably improved. Therefore, this process cartridge system is widely used in image forming apparatuses.

  In such an electrophotographic image forming apparatus in which a process cartridge is detachable and forms an image on a recording medium, a photosensitive as an electrophotographic photosensitive member provided in the process cartridge from a driving source of the image forming apparatus main body via a driving force transmitting member. Transmit the driving force to the body drum.

  As an example, the output member of the driving force transmitting member of the image forming apparatus main body is used as a gear, and the gear of the output member on the image forming apparatus main body side is engaged with a gear (referred to as a drum gear) provided on the photosensitive drum. Further, in order to drive a transfer roller for transferring a developer image formed on the photosensitive drum to a recording medium, a helical gear fixed to the photosensitive drum is meshed with a transfer roller gear provided coaxially with the transfer roller (patent) Reference 1).

In addition, there is a configuration in which a belt and a pulley are used as a transmission member that transmits driving force from a driving source of the image forming apparatus main body to a photosensitive drum included in a process cartridge (see Patent Document 2).
Japanese Patent No. 2851861 JP-A-4-368964

  Conventionally, the smooth driving force transmission from the electrophotographic photosensitive member to the transfer roller, which was desired at that time, was sufficiently satisfied. However, in order to satisfy the reduction in rotation unevenness and vibration between the electrophotographic photosensitive member and the transfer roller, which have been required in recent years, further smooth transmission of driving force from the electrophotographic photosensitive member to the transfer roller is required. Became.

  The present invention is a further development of the above-described conventional technique, and is a process cartridge that is detachably mounted on an image forming apparatus main body of an electrophotographic image forming apparatus that forms an image on a recording medium. It is an object of the present invention to provide a process cartridge that enables smooth transmission of driving force to a transfer roller on the apparatus main body side.

  Also, in an electrophotographic image forming apparatus in which a process cartridge is detachably attached to an image forming apparatus main body and an image is formed on a recording medium, a driving force is transmitted from an electrophotographic photosensitive member of the process cartridge to a transfer roller on the apparatus main body side. An object of the present invention is to provide an electrophotographic image forming apparatus capable of facilitating smoothing.

A typical configuration of the process cartridge according to the present invention is as follows:
An electrophotographic image forming apparatus main body having a main body driving means, a transfer roller for transferring a developed image to a recording medium, and a transfer roller pulley for driving the transfer roller, and forming an image on the recording medium. In a process cartridge that is detachably mounted,
An electrophotographic photoreceptor;
Developing means for developing the latent image formed on the electrophotographic photosensitive member with a developer;
A driving receiver connected to the main body driving means to transmit a driving force to the electrophotographic photosensitive member;
A photosensitive pulley driven by the driving force received by the electrophotographic photosensitive member from the drive receiving portion;
A drive transmission belt that engages with the photosensitive pulley, and when the process cartridge is mounted on the apparatus main body, engages with the transfer roller pulley so that a winding angle between the photosensitive pulley and the drive transmission belt is increased. An increased drive transmission belt;
A process cartridge characterized by comprising:

Further, a representative configuration of the electrophotographic image forming apparatus according to the present invention is an electrophotographic image forming apparatus in which a process cartridge is detachably attached to an image forming apparatus main body and an image is formed on a recording medium.
(I) main body driving means;
(Ii) a transfer roller for transferring the developed image to the recording medium;
(Iii) a transfer roller pulley for driving the transfer roller;
(Iv) an electrophotographic photosensitive member, a developing unit that develops a latent image formed on the electrophotographic photosensitive member with a developer, and a drive that is connected to the main body driving unit and transmits a driving force to the electrophotographic photosensitive member. A receiving portion, a photosensitive pulley driven by the driving force received by the electrophotographic photosensitive member from the driving receiving portion, and a drive transmission belt engaged with the photosensitive pulley, wherein the process cartridge is the device A mounting means for detachably mounting a process cartridge having a drive transmission belt that engages with the transfer roller pulley to increase a winding angle between the photosensitive pulley and the drive transmission belt when mounted on a main body;
(V) conveying means for conveying the recording medium;
An electrophotographic image forming apparatus, comprising:

  According to the present invention, the driving force transmission from the electrophotographic photosensitive member to the transfer roller can be smoothed by rotationally driving the transfer roller using the drive transmission belt. Unevenness of rotation and vibration can be reduced.

  Embodiments of a process cartridge and an electrophotographic image forming apparatus according to the present invention will be described below with reference to the drawings.

(First embodiment)
[Entire configuration of electrophotographic image forming apparatus]
First, an electrophotographic image forming apparatus to which a process cartridge constructed according to the present invention can be attached and detached will be described with reference to FIGS.

  1 is a schematic configuration diagram showing the configuration of an embodiment of an electrophotographic image forming apparatus, FIG. 2 is an external perspective view of the apparatus, FIG. 3 is an external perspective view of a cartridge mounting portion of the apparatus main body as viewed from the left side, and FIG. Is an external perspective view of the cartridge mounting portion of the apparatus main body as viewed from the right side, FIG. 5 is an external perspective view of the process cartridge as viewed from the left side cover side, and FIG. 6 is an external perspective view of the process cartridge as viewed from the right side cover side. FIG. 7 is a longitudinal sectional view showing the configuration of an embodiment of the cartridge.

  The electrophotographic image forming apparatus according to this embodiment is a laser beam printer that forms an image on a recording medium such as recording paper, an OHP sheet, or a cloth using an electrophotographic image forming process. Specifically, a laser beam La corresponding to image information is transmitted from an optical means 101 having a laser diode, a polygon mirror, a lens, a reflection mirror, and the like to the electrophotographic image forming apparatus main body C. (Simply referred to as a photosensitive drum) 107 is irradiated. As a result, an electrostatic latent image corresponding to the image information is formed on the photosensitive drum 107. This latent image is developed by a developing device using a developer (hereinafter, also simply referred to as toner) to form a visible image, that is, a toner image.

  On the other hand, in synchronization with the formation of the toner image, the recording medium 102 set in the paper feed cassette 103a is conveyed to the transfer position by the pickup roller 103b and the conveyance roller pairs 103c, 103d, and 103e. A transfer roller 104 as a transfer unit is disposed at the transfer position, and a toner image (development image) on the photosensitive drum 107 is transferred to the recording medium 102 by applying a voltage.

  The recording medium 102 that has received the transfer of the toner image is conveyed to a fixing means (fixing device) 105 via a conveyance guide 103f. The fixing unit 105 includes a driving roller 105c and a fixing roller 105b including a heater 105a. The fixing unit 105 fixes the transferred toner image on the recording medium 102 by applying heat and pressure to the recording medium 102 that passes therethrough. . The recording medium 102 on which the toner image has been fixed by the fixing unit is then conveyed by the discharge roller pair 103g and 103h, and is discharged to the discharge tray 106 via the reverse path 103i. The discharge tray 106 is provided on the upper surface of the apparatus main body C.

  In the image forming apparatus shown in the present embodiment, the swingable flapper 103j can be operated to discharge the recording medium 102 to the discharge tray 106a provided on the side surface of the apparatus main body C without passing through the reverse path 103i. Further, the pickup means 103b, the conveyance roller pairs 103c, 103d, 103e, the conveyance guide 103f, the discharge roller pairs 103g, 103h, and the like constitute the conveyance means 103 for the recording medium 102.

[Process cartridge]
The process cartridge is provided with an electrophotographic photosensitive member and at least one process means acting thereon. Here, as the process means, for example, charging means for charging the electrophotographic photosensitive member, developing means for developing the electrostatic latent image formed on the electrophotographic photosensitive member, and cleaning the peripheral surface of the electrophotographic photosensitive member. There are cleaning means.

  As shown in FIG. 7, the process cartridge D (hereinafter referred to as cartridge D) shown in the present embodiment includes a photosensitive drum 107, a charging unit 108, a developing unit 122, and a cleaning unit 117. is there. The photosensitive drum 107 is uniformly charged by applying a voltage from a charging roller 108 which is a charging unit on the peripheral surface of the drum. The above-mentioned laser beam light La is irradiated onto the drum peripheral surface through an exposure opening (not shown). As a result, an electrostatic latent image is formed on the circumferential surface of the photosensitive drum. The latent image is developed with toner by the developing roller 110 of the developing unit 122.

  The developing means 122 is a developing sleeve 110 as a developer carrying member, and development as a toner amount regulating member for imparting triboelectric charge to the toner on the peripheral surface of the developing sleeve 110 and forming a toner layer having a predetermined thickness. A blade 112 and a magnet roller 111 built in the developing sleeve 110 are provided. Each of these components is held by the developing device frame 113. The developing frame 113 is welded and integrated with a toner storage container 114 that stores toner to form a developing device unit 119 together with the container.

  An agitating member 115 for agitating the toner and feeding the toner to the developing chamber 113 a in the developing frame 113 is provided in the toner container 114. The toner in the toner container 114 is sent out to the developing sleeve 110 in the developing chamber 113 a by the rotation of the stirring member 115. In the developing frame 113, a toner stirring member 116 is provided in the vicinity of the developing sleeve 110, and the toner in the developing chamber 113a is stirred and circulated by the rotation of the toner stirring member. With this configuration, the toner t stored in the toner storage container 114 is sent out to the developing chamber 113 a by the rotation of the stirring member 115. Then, the toner is fed into the developing sleeve 110 while being agitated by the toner agitating member 116 in the developing chamber 113a. This toner adheres to the peripheral surface of the developing sleeve 110 containing the magnet roller 111 and is conveyed by the rotation of the developing sleeve 110. Then, a triboelectric charge is imparted by the developing blade 112 and a toner layer having a predetermined thickness is formed on the developing sleeve 110 and conveyed to the developing area of the photosensitive drum 107. The toner supplied to the development area is transferred to a latent image on the photosensitive drum 107 to form a toner image. The developing sleeve 110 is connected to a developing bias circuit, and normally, a developing bias voltage in which a DC voltage is superimposed on an AC voltage is applied.

  The cleaning unit 117 removes residual toner on the photosensitive drum 107 after the toner image is transferred to the recording medium 102 by the transfer roller 104. That is, the residual toner on the photosensitive drum 107 is scraped off by the elastic cleaning blade 117a brought into contact with the photosensitive drum 107 and collected in the waste toner reservoir 117b. The photosensitive drum 107 from which the residual toner has been removed is subjected to the next image forming process.

  Each member such as the photosensitive drum 107 is housed in a unit in which the toner container 114, the developing frame 113, and the drum frame 118 are combined to form a cartridge. That is, the stirring member 115 is stored and held in the toner storage container 114. The developing sleeve 110, the developing blade 112, the toner stirring member 116, and the like are stored and held in the toner storage container 114. The toner container 114 and the developing device frame 113 are integrated by welding or the like to constitute the developing device unit 119. The photosensitive drum 107, the cleaning blade 117a, the charging roller 108, and the like are housed and held in the drum frame 118 to constitute the photosensitive unit 120. As shown in FIG. 5, the developing device unit 119 and the photosensitive unit 120 are sandwiched from both sides by the left side cover 140 and the right side cover 141 and are integrally combined to form a cartridge.

[Photosensitive unit]
FIG. 8 is an exploded perspective view of a structure for attaching the photosensitive drum 107 to the drum frame 118. A gear flange 107a is attached to one end of the photosensitive drum 107, and a drum pulley 107b as a photosensitive pulley is attached to the other end. The gear flange 107a is rotatably supported by the drum bearing 124. The drum pulley 107b is rotatably supported by the drum pulley bearing 125. The drum bearing 124 and the drum pulley bearing 125 are attached to the side plates 118a and 118b of the drum frame 118 by screws 128, respectively. As a result, the photosensitive drum 107 is incorporated into the photosensitive unit 120.

  The gear flange 107a has a twisted triangular convex coupling portion 107a1 (FIG. 6) as a drive receiving portion at its end. The coupling portion 107a1 is supported by the support hole 124a of the drum bearing 124. In the drum bearing 124, a cylindrical guide 124b provided around the support hole 124a is fitted into the opening 141a (FIG. 6) of the right side cover 141. Thereby, the cylindrical guide 124b and the coupling part 107a1 are exposed to the outside. This coupling part 107a1 is connected to a coupling part 131 (FIG. 4) as a main body driving means provided in the apparatus main body C. As a result, a rotational driving force is applied to the coupling portion 107a1 from the apparatus main body side, and the coupling portion 107a1 rotationally drives the photosensitive drum 107.

  The drum pulley 107b is a toothed pulley having a tooth portion on the tip circumference, and is supported by the support hole 125d of the drum pulley bearing 125 so as to expose the tooth portion. The drum pulley bearing 125 has a cylindrical portion 125c around the support hole 125d. The cylindrical portion 125c is integrally provided with a shaft portion (guide means) 125a via a connecting plate 125b. The shaft portion 125a is positioned approximately at the center of the support hole 125d by the connecting plate 125b. The end of the drum pulley 107b side is accommodated in the pulley hole 107b2 when the drum pulley bearing 125 is attached. The cylindrical portion 125c of the drum pulley bearing 125 is fitted into the opening 140a (FIG. 5) of the left side cover 140. As a result, the shaft portion 125a of the drum pulley bearing 125 is exposed to the outside.

[Process cartridge drive transmission mechanism]
Next, the configuration of the drive transmission mechanism provided in the cartridge D will be described. As shown in FIG. 5, a drive transmission belt 150 for driving the transfer roller 104 is provided on the side surface of the left side cover 140 of the cartridge D. The drive transmission belt 150 is a double-sided toothed belt made of an elastic member such as rubber, and is wound around a drum pulley 107b as a photosensitive pulley, a fixed pulley 151, a moving pulley 152 as a movable pulley, and a tension pulley 153. . The fixed pulley 151 and the moving pulley 152 are toothed pulleys each having a tooth portion on the circumference. Therefore, the drive transmission belt 150 is wound around the pulleys 107b, 151, and 152 in a state where the teeth are meshed on the inner peripheral surface. The tension pulley 153 is rotatably supported by the pulley holder 158. The pulley holder 158 is slidably attached to the side cover 140. The pulley holder 158 is pressurized by the pressure spring 159, so that the tension pulley 153 applies tension to the drive transmission belt 150. The fixed pulley 151 is rotatably attached to a fixed shaft 156 on the side surface of the cartridge D. The moving pulley 152 is rotatably attached to a swing shaft (rotary shaft) 157 of the swing arm 154. The material of the drum pulley 107b, the fixed pulley 151, the moving pulley 152, the tension pulley 153, and the swing arm 154 may be resin or metal. For example, POM, PC, PS, etc. are used.

  The end of the swing arm 154 opposite to the swing shaft 157 is rotatably attached to the fixed shaft 156. An arm pressurizing spring 155 is stretched between the swing shaft 157 and the shaft 140 a provided on the left side cover 140. The arm pressing spring 155 is below the imaginary line L connecting the center of the fixed shaft 156 and the center of the shaft 140. Therefore, the arm pressurizing spring 155 presses the swing arm 154 in the direction of the arrow h that separates the swing arm 154 from the drum pulley 107b. The swing arm 154 pressed by the arm pressing spring 155 is stopped by being locked by a stopper (not shown) provided on the side cover 140. At this time, the moving pulley 152 is also below the virtual line L.

[Mounting configuration of transfer roller]
FIG. 9 is a perspective view showing the configuration of an embodiment of the apparatus main body attachment portion of the transfer roller 104. FIG. The transfer roller 104 has shafts 104a and 104b at both ends thereof. These shafts 104a and 104b are rotatably supported by transfer roller bearings 161 and 162, respectively. The transfer roller bearing 162 rotatably supports the shaft 104b of the transfer roller 104 and is a cylindrical restricting portion that restricts the position of the bearing portion 162b serving as an attaching portion to the apparatus main body and the swing arm 154 of the cartridge D. 162a is integrally provided. Transfer roller pressure springs 163 and 164 are attached to the transfer roller bearings 161 and 162, respectively.

  The transfer roller bearings 161 and 162 that support the transfer roller 104 are respectively attached to the attachment portions 165a and 165b of the apparatus main body with arrows a and arrow a ′ that allow the transfer roller to be separated from and contacted with the photosensitive drum 107. It is slidably mounted in the direction. The transfer roller bearings 161 and 162 are urged in the direction of arrow a by the pressure springs 163 and 164, so that the transfer roller 4 is pressed against the photosensitive drum 107 with a predetermined pressure. A transfer roller pulley 160 for receiving a driving force from the drive transmission belt 150 of the cartridge D is attached to the shaft 104 b of the transfer roller 104. The pulley 160 is a toothed pulley that meshes with the teeth on the outer peripheral surface of the drive transmission belt 150.

[Process cartridge positioning mechanism]
Next, driving and guide of the cartridge D and positioning means will be described. As shown in FIG. 2, when the cartridge door 109 of the apparatus main body C is opened in the direction of the arrow about the shaft 109a, the upper part of the apparatus main body is opened. When the cartridge D is not attached, the cartridge attachment portion S looks as shown in FIGS. Guide members 130L and 130R as main body guide means (mounting means) are provided on the left and right inner walls of the apparatus main body C from the opening where the cartridge door 109 is opened. That is, as shown in FIG. 3, the guide member 130L is provided on the left side when viewed from the direction in which the cartridge D is attached and detached, and the guide member 130R and the coupling portion 131 are provided on the right side as shown in FIG. The coupling part 131 of the apparatus main body C has a twisted triangular concave shape. The coupling unit 131 is connected to a drive motor in the apparatus main body, and receives a rotational driving force.

  As shown in FIGS. 3 and 4, the guide members 130L and 130R are respectively provided in the guide portions 130La and 130Ra which are obliquely inclined so as to be lowered forward when viewed from the insertion direction of the cartridge D, and the guide portions 130La and 130Ra, respectively. Semi-circular positioning grooves 130Lb and 130Rb are provided. The guide portion 130La guides the shaft portion 125a (FIG. 5) on the left side cover 140 side of the cartridge D to the positioning groove 130Lb. On the other hand, the guide portion 130Ra guides the cylindrical guide 124b (FIG. 6) on the right side cover 141 side of the cartridge D to the positioning groove 130Rb. The guide portion 130Ra also guides a detent guide 141c (FIG. 6) provided on the right side cover 141 in the vicinity of the cylindrical guide 124b. Therefore, the cartridge D can be detachably mounted on the apparatus main body C in the front lowering direction of the guide portions 130La and 130Ra, that is, the direction intersecting the recording medium conveyance direction (the direction of arrow e shown in FIG. 1).

  Each of the positioning grooves 130Lb and 130Rb has a cylindrical shape that comes into contact with the outer peripheral surface of the corresponding shaft portion 125a and cylindrical guide 124b. The centers of the positioning grooves 130Lb and 130Rb coincide with the centers of the shaft portion 125a and the cylindrical guide 124b of the cartridge D and the center line of the photosensitive drum 107 when the cartridge D is mounted on the apparatus main body C.

[Combination of drive transmission mechanism and transfer roller pulley]
FIG. 11 is an explanatory view of the operation of the drive transmission mechanism as the cartridge D is inserted into the apparatus main body C. 12A is an enlarged perspective view of the drive transmission belt and the transfer roller pulley shown in FIG. 11B, and FIG. 12B is an enlarged perspective view of the drive transmission belt and the transfer roller pulley shown in FIG. 11C.

  As shown in FIG. 11A, when the cartridge D is mounted on the apparatus main body C, the cartridge D is lowered downward when viewed from the insertion direction, the shaft portion 125a of the drum pulley bearing 125 is used as the guide portion 130La, and the drum bearing 124 ( A cylindrical guide 124b (not shown) and a non-rotating guide 141c are inserted in the direction of arrow e along the guide portion 130Ra (not shown). The shaft portion 125a, the cylindrical guide 124b, and the anti-rotation guide 141c of the cartridge D proceed to the back side of the cartridge mounting portion S along the guide portions 130Ra and 130La.

  As shown in FIG. 11B, in the cartridge D, the outer peripheral surface of the drive transmission belt 150 contacts the transfer roller pulley 160 between the drum pulley 107b and the moving pulley 152 in the above insertion process. That is, the upstream side of the transfer roller pulley 160 contacts the drive transmission belt 150 with respect to the cartridge mounting direction. In this state, as shown in FIG. 12A, the arm pressing spring 155 is below the imaginary line L, and presses the swing arm 154 in the direction of the arrow h. When the cartridge D is further inserted while the drive transmission belt 150 is in contact with the transfer roller pulley 160, the drive transmission belt 150 is pushed by the transfer roller pulley 160 in a direction opposite to the insertion direction e (in the direction of arrow f in the drawing). At this time, the drive transmission belt 150 is bent and deformed in the direction of arrow f between the drum pulley 107b and the moving pulley 152. Then, the tension of the drive transmission belt 150 according to the bending deformation acts as a rotational moment on the swing arm 154 via the moving pulley 152. Then, the swing arm 154 starts to rotate in the direction of the arrow g (clockwise direction) around the fixed shaft 156 against the pressure applied by the arm pressurizing spring 155.

  When the cartridge D is further inserted, the drive transmission belt 150 is wound around the transfer roller pulley 160 as shown in FIG. 11C, and the cartridge D is attached to the apparatus main body C. That is, as the cartridge D is inserted, the swing arm 154 rotates around the fixed shaft 156 in the direction of arrow g (clockwise direction), and the drive transmission belt 150 is wound around the upstream side of the transfer roller pulley 160. In this state, as shown in FIG. 12B, the arm pressure spring 155 is above the imaginary line L and presses the swing arm 154 in the direction of arrow i. At this time, an arcuate positioning portion 154 a provided integrally with the swing arm 154 abuts on a cylindrical regulating portion 162 a provided integrally with the transfer roller bearing 162. As a result, the transfer roller pulley 160 and the moving pulley 152 are positioned relative to each other. With this configuration, the drive transmission belt 150 can be wound around the transfer roller pulley 160 by the pulling force of the arm pressure spring 155, so that the mounting force for mounting the cartridge D on the apparatus main body C can be reduced. Wearability of D is improved. When the shaft portion 125a and the cylindrical guide 124b of the cartridge D reach the positioning grooves 130Lb and 130Rb of the apparatus main body C in a state where the drive transmission belt 150 is wound around the transfer roller pulley 160, the shaft portion 125a and the cylindrical guide 124b are positioned. Sitting at the positions of the grooves 130Lb and 130Rb, the respective positions are determined. Thus, the non-driving side (drum pulley 107b side) of the cartridge D is positioned with respect to the apparatus main body C, and the driving side (gear flange 107a side) of the cartridge D is substantially positioned with respect to the apparatus main body C. At the time of driving transmission from the motor of the apparatus main body to the photosensitive drum 107, the photosensitive drum 107 is finally aligned by the coupling portion 131 of the apparatus main body and the coupling portion 107a1 of the gear flange 107a of the cartridge D. D is positioned. As described above, the cartridge D is mounted on the apparatus main body.

  When removing the cartridge D from the apparatus main body C, the cartridge door 109 is opened and the cartridge D is pulled up in the direction opposite to the insertion direction. As a result, the shaft 125a, the cylindrical guide 124b, and the anti-rotation guide 141c of the cartridge D are moved to the front side of the cartridge mounting portion S in the order of FIGS. 11C, 11B, and 11A along the guide portions 130Ra and 130La. Moved. When shifting from the state shown in FIG. 11C to the state shown in FIG. 11B, the positioning part 154a of the swing arm 154 moves the restricting part 162a to the arrow as shown in FIG. 12B as the guide parts 130Ra and 130La move. Get over the direction of j. At that time, the arm pressurizing spring 155 comes below the imaginary line L (FIG. 12A). As a result, the swing arm 154 is pressurized by the arm pressure spring 155 and returns to its original position. Therefore, the cartridge D can be detached from the apparatus main body C without the drive transmission belt 150 being loosened.

[Transmission of driving force from photoconductor drum to transfer roller]
The drive configuration of the transfer roller 104 will be described with reference to FIG. FIG. 10 is a view showing a state where the cartridge D is mounted on the apparatus main body (only the cartridge and the transfer roller portion are shown in the figure).

  When the cartridge D is mounted, the drive transmission belt 150 of the cartridge D is wound around the transfer roller pulley 160. At the same time, when the cartridge D is mounted on the apparatus main body C, the winding angle between the drive transmission belt 50 and the drum pulley 107b increases. As the winding angle increases, the meshing rate between the drive transmission belt 50 and the drum pulley 107b increases, and the drive to the transfer roller can be transmitted smoothly and stably. In this state, the photosensitive drum 107 receives a driving force from the apparatus main body and is rotationally driven in the arrow b direction (clockwise direction). As a result, the drum pulley 107b rotates in the same direction to move the drive transmission belt 105 in the direction of arrow c (clockwise direction). The drive transmission belt 105 drives the transfer roller 104 to rotate in the arrow d direction (counterclockwise direction) via the transfer roller pulley 160.

  As described above, in this embodiment, the drive transmission belt 150 and the transfer roller pulley 160 are compared with the system in which the transfer roller 104 is rotated using the drive transmission belt 150 and the transfer roller is rotated by a gear. The number of meshing teeth can be increased. Further, the tension of the drive transmission belt 150 is adjusted by the tension pulley 153 described above even when the recording medium passes between the transfer roller 104 slidably mounted as described above and the photosensitive drum 107 and the distance between the axes fluctuates. Is done. Therefore, the meshing state of the teeth of the drive transmission belt 150 and the transfer roller pulley 160 is stabilized. Therefore, the driving force can be smoothly transmitted from the photosensitive drum 107 to the transfer roller 104, and uneven rotation and vibration of the photosensitive drum 107 and the transfer roller 104 can be reduced to obtain a good image.

  Further, if the drive transmission belt 150 is a double-sided toothed belt and the upstream side of the transfer roller pulley 160 is engaged with the drive transmission belt 150 with respect to the mounting direction of the cartridge D, the cartridge D extends along the guide portions 130Ra and 130La. By simply pushing in, the drive transmission belt 150 and the transfer roller pulley 160 are engaged with each other, so that the mountability of the cartridge D is not impaired.

  In addition, since the drive transmission belt 150 is provided in the cartridge D, when replacing the transfer roller 104, it is not necessary to remove the drive transmission belt 150 from the drive transmission belt 150, and workability is not impaired.

  When the cartridge D is mounted on the apparatus main body C and the drive transmission belt 150 is wound around the transfer roller pulley 160, the tension of the drive transmission belt 150 acts as a force in the direction of removing the cartridge D from the apparatus main body C. For this reason, in this embodiment, the contact portion between the positioning portion 154a of the swing arm 154 and the restricting portion 162a receives this force to prevent the cartridge D from coming off. Therefore, it is not necessary to provide a separate stopper for the cartridge D, and the number of parts can be reduced.

  Further, by providing the tension pulley 153, the pressure fluctuation of the transfer roller 104 due to the fluctuation of the tension of the drive transmission belt 150 can be suppressed small.

  Further, by providing the transfer roller pulley 160 and the regulating portion 162a for regulating the position of the swing arm 154 provided with the moving pulley 152 on the same axis, the positions of the transfer roller pulley 160 and the moving pulley 152 can be accurately determined. it can.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS.

[Process cartridge]
FIG. 13 is an external perspective view of the process cartridge F according to the second embodiment on the left side cover side. Similar to the cartridge D of the first embodiment, the process cartridge F is integrally formed into a cartridge by connecting the developing device unit 170 and the photosensitive unit 171 with the left side cover 172 and the right side cover 173.

[Process cartridge drive transmission mechanism]
The configuration of the drive transmission mechanism provided in the cartridge F will be described with reference to FIGS. FIG. 14 is a diagram showing an embodiment of the drive transmission mechanism, an exploded perspective view of the drive transmission mechanism, and FIG. 15 is a perspective view showing a configuration of the drive transmission mechanism.

  A drive transmission belt 175 for driving a transfer roller 174 (not shown) is provided on the side surface of the left side cover of the cartridge F. The drive transmission belt 175 is a belt with double-sided teeth and is wound around a drum pulley 176b as a photosensitive pulley, a first moving pulley 177 as a first movable pulley, and a second moving pulley 178 as a second movable pulley. Yes. Each of the pulleys 176b, 177, 178 is a toothed pulley having a tooth portion on the circumference. Therefore, the drive transmission belt 175 is wound around the pulleys 176b, 177, 178 in a state where the teeth are meshed with each other on the inner peripheral surface. Here, the first moving pulley 177 is attached to a first moving shaft (rotating shaft) 181 provided on a disc-shaped first swing arm 179 that is provided coaxially with the photosensitive drum 107 (FIG. 15). It is provided so as to be rotatable. The second moving pulley 178 is rotatably provided on the second moving shaft (rotating shaft) 182 of the second swing arm 180 provided rotatably on the first moving shaft 181.

  As shown in FIGS. 14 and 15, the side cover 172 has two arcuate guide grooves 172d and 172e concentric with the axial center of the drum pulley 176b. Of the arc-shaped guide grooves 172d and 172e, one guide groove 172d holds the end of the first moving shaft 181 so as to be movable, and the other guide groove 172e holds the end of the second moving shaft 182 so as to be movable. . The first swing arm 179 engages one end 183a of the torsion coil spring 183 disposed on the circumference of the cylindrical portion 200c of the drum pulley bearing (not shown) with the engagement portion 172c of the left side cover 172, and the other end 183b. The first swing arm 179 is engaged with the groove 179a. As a result, the first swing arm 179 is urged to rotate in the direction of the arrow k (clockwise direction) with respect to the axial center of the drum pulley 176b. The position of the first swing arm 179 is determined by abutting the contact portion 179b provided on the arm against the stopper 172a of the left side cover 172. The first moving shaft 181 is urged in the same direction as the first swing arm 179 and comes into contact with the locking portion 172d1 at the upper end of the guide groove 172d.

  In addition, the second swing arm 180 has one end and the other end of the torsion coil spring 184 disposed on the outer periphery of the first moving shaft 181 between the second swing arm 180 and the first moving pulley 177, respectively. The locking portion 179c and the locking portion 180a of the second swing arm 180 are locked. As a result, the second swing arm 180 is urged to rotate in the direction of arrow I (clockwise direction) with respect to the first moving shaft 181, thereby applying tension to the drive transmission belt 175. The second moving shaft 182 is urged in the same direction as the second swing arm 180 and comes into contact with the locking portion 172e1 at the upper end of the guide groove 172e. Since the configuration of the gear flange and the coupling portion on the right side cover 173 side of the cartridge F is the same as that of the first embodiment, the description thereof is omitted.

[Image forming device body]
FIG. 16 is a perspective view showing the left side of the cartridge mounting portion S1 of the apparatus main body E to which the cartridge F can be attached and detached. When the cartridge F is attached to the apparatus main body E, the cartridge door 185 of the apparatus main body E is opened as shown in the figure, and the guide portion 186La formed on the guide member 186L of the apparatus main body E is attached to the left side cover 172 side of the cartridge F. A shaft portion (guide means) 172b (FIG. 13) of the drum pulley bearing is inserted. The configuration of the guide member and the coupling portion on the right side of the cartridge mounting portion S1 of the apparatus main body E is the same as that of the first embodiment, and the description thereof is omitted.

  FIG. 17 is a configuration diagram showing an embodiment of a gear mechanism provided in the left rear part of the cartridge mounting portion S1 of FIG. A transfer roller 174 is slidably attached to the apparatus main body E as in the first embodiment. A transfer roller pulley 190 for driving the transfer roller is attached to one end of the transfer roller 174. Note that the mounting structure of the transfer roller 174 to the apparatus main body E is the same as that of the first embodiment, so that the description thereof is omitted.

  Next, the gear mechanism will be described. The cartridge door 185 of the apparatus main body E rotates around the shaft 185a and opens and closes. The cartridge door 185 has a fan-shaped gear 185b that rotates about a shaft 185a. The gear 185b rotates in conjunction with opening and closing of the cartridge door 185. The gear 185 b meshes with a first gear 187 provided in the apparatus main body E. The first gear 187 meshes with a second gear 188 provided in the apparatus main body E. Further, the apparatus main body E is provided with a slider 189 slidable in the direction of an arrow m perpendicular to the recording medium conveyance direction. The slider 189 has a rack portion 189 b, and this rack portion 189 b meshes with the second gear 188. The slider 189 has a guide portion 189a for engaging the first moving shaft 181 of the cartridge F on the opposite side of the rack portion 189b. And the front end surface of the guide piece 189c provided above the guide part 189a is formed in the slope 189d which inclines in the back part of this guide part.

[Combination of drive transmission mechanism and transfer roller pulley]
Next, the coupling mode of the drive transmission mechanism and the transfer roller pulley will be described with reference to FIG. 18A shows a state where the cartridge door 185 is opened and the cartridge F is mounted on the apparatus main body E, and FIG. 18B shows a state where the cartridge door 185 of the apparatus main body E is closed after the cartridge F is mounted. It is. (A), (b) is the figure which looked at the apparatus main body E from the arrow r direction of FIG. 16, and the guide member 186 and the guide part 186a have shown the position with the broken line for description of an inside. Since the relationship between the cylindrical guide of the right side cover 173 of the cartridge F and the guide member of the apparatus main body E that guides the same is the same as that of the first embodiment, the description thereof is omitted.

  When the shaft portion 172b on the left side cover 172 side of the cartridge F is inserted in the direction of the arrow p along the guide portion 186a of the apparatus main body E, the first moving shaft 181 contacts the inclined surface 189d of the slider 189. When the cartridge F is further pushed in, the first moving shaft 181 is accommodated in the guide portion 189a of the slider 189 while the first swing arm 179 rotates counterclockwise, and the state shown in FIG. That is, when the cartridge F is further pushed in with the first moving shaft 181 in contact with the inclined surface 189d of the slider 189, the first moving shaft 181 moves along the inclined surface 189d. At this time, the first moving shaft 181 is guided to the inner part of the cartridge mounting portion S1 by the inclined surface 189d. As a result, a counterclockwise force acts against the biasing force of the torsion coil spring 183 from the first moving shaft 181 to the first swing arm 179, and the first swing arm 179 is rotated counterclockwise. As a result, the first moving shaft 181 begins to move to the back side along the guide groove 172d. When the first moving shaft 181 is detached from the inclined surface 189d, the first moving shaft 181 enters the guide portion 189a of the slider 189. When the first moving shaft 181 enters the guide portion 189a, the shaft portion 172b reaches the positioning groove 186b of the apparatus main body E. At this time, the first swing arm 179 stops rotating, and the first moving shaft 181 stops at a predetermined position in the guide portion 189a.

  After the cartridge F is mounted on the apparatus main body E, when the shaft 185a is rotated to close the cartridge door 185, the gear 185b rotates in the direction of arrow n (clockwise direction). The gear 187 rotates counterclockwise according to the rotation of the gear 185b, and the gear 188 rotates clockwise according to the rotation of the gear 187. Then, the slider 189 slides in the direction of arrow q (downward) according to the rotation of the gear 188. As the slider 189 slides, the first moving shaft 181 starts to move along the guide groove 172d. When the cartridge door 185 is further rotated, the slider 189 is further slid in the arrow q direction by the rotation of the gears 185b, 187, and 188 as described above, and the moving shaft 181 is further moved along the guide groove 172d. In the sliding process of the slider 189, the first moving shaft 181 is released from the guide groove 172d while being held by the guide portion 189a, and the second moving shaft 182 is released from the guide groove 172e. The outer peripheral surface of the drive transmission belt 175 comes into contact with the transfer roller pulley 190 attached to the transfer roller 174 as indicated by a one-dot chain line between the drum pulley 176 b and the second moving pulley 178. That is, the downstream side of the transfer roller pulley 190 is in contact with the drive transmission belt 190 with respect to the cartridge mounting direction.

  As shown in (b), when the cartridge door 185 is completely closed, the slider 189 further slides in the direction of the arrow q from the position indicated by the one-dot chain line in (a) by the rotation of the gears 185b, 187, and 188. At this time, the slider 189 slides with the drive transmission belt 175 in contact with the transfer roller pulley 190. As a result, the drive transmission belt 175 receives a force in the insertion direction p from the transfer roller pulley 190. As a result, the second swing arm 180 rotates counterclockwise from the position indicated by the alternate long and short dash line in (a) with the first moving shaft 181 as a fulcrum against the urging force of the coil spring 184. As a result, the drive transmission belt 175 is wound around the transfer roller pulley 190. At this time, the arc-shaped positioning portion 180 b provided on the second swing arm 180 abuts on a cylindrical regulating portion 191 a provided integrally with the transfer roller bearing 191. As a result, the transfer roller pulley 190, the first moving pulley 177, and the second moving pulley 178 are positioned relative to each other.

  In a state where the drive transmission belt 175 is wound around the transfer roller pulley 190, the photosensitive drum 176 is aligned and the cartridge F is positioned as in the first embodiment. Thus, the cartridge F is mounted on the apparatus main body E. As a result, the drive can be transmitted from the drive transmission belt 175 to the transfer roller 190 as in the first embodiment.

  When the cartridge F is taken out from the apparatus main body E, when the cartridge door 185 is opened in (b), the gears 185b, 187, 188 are rotated in the direction opposite to the previous rotation direction. That is, the gear 188 rotates counterclockwise in accordance with the opening operation of the cartridge door 185, whereby the slider 189 is moved upward together with the first moving shaft 181. When the first swing arm 179 moves away from the transfer roller pulley 190 along with the movement of the slider 189 and the first moving shaft 181, the first swing arm 179 is rotated counterclockwise by the biasing force of the coil spring 183. Retreats from the roller pulley 190 (the state indicated by the one-dot chain line in (a)). When the slider 189 is further moved upward together with the first movement shaft 181, the first movement shaft 181 enters the guide groove 172d and the second movement shaft 182 enters the guide groove 172e. When the slider 189 is further moved upward together with the first moving shaft 181, the second moving shaft 182 is locked by the locking portion 172 e 1 of the guide groove 172 e and stopped. The first moving shaft 181 moves to the near side (opening side) along the guide portion 189a by the upward movement by the slider 189 and the clockwise rotation of the first swing arm 179 by the biasing force of the coil spring 183. The first moving shaft 181 is moved along the guide groove 172d while coming out of the guide portion 189a and in contact with the inclined surface 189d, and is stopped by being locked to the locking portion 172d1 of the guide groove (state (a)) ). In this state, the cartridge F can be removed from the apparatus main body E by pulling out the cartridge F in the direction opposite to the arrow p.

  As described above, also in this embodiment, the drive transmission belt 175 and the transfer roller pulley are driven by rotating the transfer roller 174 using the drive transmission belt 175, as compared with the system in which the transfer roller is rotationally driven by a gear. The number of meshing teeth with 190 can be increased. Therefore, the driving force can be smoothly transmitted from the photosensitive drum 176 to the transfer roller 190, and uneven rotation of the photosensitive drum 176 and the transfer roller 190 can be reduced and a good image can be obtained.

  Further, as in this embodiment, when the cartridge F is detached from the apparatus main body E, the drive transmission belt 175 is retracted to a position where it does not protrude from the outer shape of the cartridge F, so that the size of the cartridge can be reduced. it can.

  Further, by adopting a configuration in which the drive transmission belt 175 is moved in conjunction with the cartridge door 185, the tension of the drive transmission belt 175 does not become an operation load when the cartridge F is mounted or removed, thereby improving operability. Can be improved.

  Further, by adopting a configuration in which the cartridge F has the drive transmission belt 175, a drive configuration using the belt can be realized without impairing the workability of the transfer roller replacement.

  In addition, since the downstream side of the transfer roller pulley 190 meshes with the drive transmission belt 175 with respect to the mounting direction of the cartridge F, the drive transmission belt 175 and the transfer roller pulley 190 mesh with the closing operation of the cartridge door 185. A drive configuration by the drive transmission belt 175 can be realized without impairing the mountability of the cartridge F.

  Further, the transfer roller pulley 190 and the first and second moving pulleys 177 and 178 are provided on the same axis with a restricting portion 191a for restricting the position of the second swing arm 180. The positions of the second moving pulleys 177 and 178 can be determined with high accuracy.

[Other]
Even when a friction transmission belt such as a flat belt or a V belt is used as the drive transmission belts 150 and 175, the drive transmission from the drum pulleys 107b and 176b of the photosensitive drum 107 to the transfer roller pulleys 160 and 190 of the transfer rollers 104 and 174 is possible. is there. However, the rotation of the transfer roller 104 and the photosensitive drum 107 can be accurately transmitted by using a double-sided toothed belt as in this embodiment. Further, since the belt mounting tension can be reduced by using a toothed belt as compared with the friction transmission belt, the configuration can be simplified.

1 is a schematic configuration diagram illustrating a configuration of an example of an electrophotographic image forming apparatus. 1 is an external perspective view of an electrophotographic image forming apparatus. It is an external appearance perspective view which shows the structure of the left side of the mounting part of the apparatus main body for mounting | wearing with the process cartridge of a 1st Example. It is an external appearance perspective view which shows the structure of the right side of the mounting part of the apparatus main body for mounting | wearing with the process cartridge of a 1st Example. It is a left-side external perspective view of the process cartridge of the first embodiment. It is a right external perspective view of the process cartridge of the first embodiment. It is a longitudinal cross-sectional view which shows the structure of the process cartridge of a 1st Example. It is a perspective view which shows the structure of a photoconductor unit. It is a perspective view which shows the structure of a transfer roller. It is a figure which shows the drive method of the transfer roller by a drive transmission belt. It is a figure which shows the mounting process to the apparatus main body of the process cartridge of a 1st Example. FIG. 5 is an explanatory diagram of a connection form of a drive transmission belt and a transfer roller pulley in a process cartridge mounting process. It is a left external perspective view of the process cartridge of the second embodiment. It is a disassembled perspective view which shows one Example of the drive transmission mechanism of the process cartridge of a 2nd Example. It is a perspective view which shows the structure of the drive transmission mechanism. It is an external appearance perspective view which shows the structure of the left side of the mounting part of the apparatus main body for mounting | wearing with the process cartridge of a 2nd Example. It is a perspective view which shows one Example of the gear mechanism of the left inner side part of the mounting part shown in FIG. It is a figure which shows the mounting process to the apparatus main body of the process cartridge of a 2nd Example.

Explanation of symbols

C, E Electrophotographic image forming apparatus (laser beam printer) main body D, F Process cartridge 101 Optical means 102 Recording medium 103 Conveying means 104 Transfer roller 105 Fixing means 107 Photosensitive drum (electrophotographic photosensitive member)
107a Gear flange 107a1 Coupling part (drive receiving part)
107b Drum pulley (photoreceptor pulley)
108 Charging roller (charging means)
109 Cartridge door 110 Developing sleeve (developer carrier)
111 Magnet roller 112 Developing blade (regulating member)
113 Development frame body 113a Development chamber 114 Toner storage container (developer storage container)
115 Agitating member 116 Toner agitating member 117 Cleaning means 117a Cleaning blade 117b Waste toner reservoir 118 Drum frame 118a, 118b Side plate 119 Developing device unit 120 Photosensitive unit 122 Developing means 124 Drum bearing 125 Drum pulley bearing 125a Shaft (guide means)
130L, 130R Guide member 131 Coupling part (drive means)
140 Side cover (L)
140a shaft 141 side cover (R)
150 Drive transmission belt 151 Fixed pulley 152 Moving pulley (movable pulley)
153 Tension pulley 154 Swing arm 154a Positioning part 155 Arm pressure spring 156 Fixed shaft 157 Swing shaft 158 Pulley holder 159 Pressure spring 160 Transfer roller pulley 161, 162 Transfer roller bearing 162a Restriction unit 162b Bearing unit 163, 164 Transfer roller pressure Spring 170 Developing device unit 171 Photoconductor unit 172 Side cover (L)
172a Stopper 172b Shaft (guide means)
172c Engagement part 173 Side cover (R)
174 Transfer roller 175 Drive transmission belt 176b Drum pulley (photoreceptor pulley)
177 First moving pulley (movable pulley)
178 Second moving pulley (movable pulley)
179 First swing arm 179a Groove 179b Contact portion 179c Locking portion 180 Second swing arm 180c Locking portion 181 First moving shaft 182 Second moving shaft 183, 184 Torsion coil spring 183a Torsion coil spring one end 183b Torsion coil spring 185 Cartridge door 185a Shaft 185b Gear 186L Guide member 186La Guide portion 187, 188 Gear 189 Slider 189a Guide portion 190 Transfer roller pulley 191 Transfer roller bearing 191a Restriction portion

Claims (11)

An electrophotographic image forming apparatus main body having a main body driving means, a transfer roller for transferring a developed image to a recording medium, and a transfer roller pulley for driving the transfer roller, and forming an image on the recording medium. In a process cartridge that is detachably mounted,
An electrophotographic photoreceptor;
Developing means for developing the latent image formed on the electrophotographic photosensitive member with a developer;
A driving receiver connected to the main body driving means to transmit a driving force to the electrophotographic photosensitive member;
A photosensitive pulley driven by the driving force received by the electrophotographic photosensitive member from the drive receiving portion;
A drive transmission belt that engages with the photosensitive pulley, and when the process cartridge is mounted on the apparatus main body, engages with the transfer roller pulley so that a winding angle between the photosensitive pulley and the drive transmission belt is increased. An increased drive transmission belt;
A process cartridge comprising: Furthermore, the process cartridge includes:
A movable pulley that is movably provided to engage with the drive transmission belt, and that moves in a direction that increases the winding angle when the process cartridge is mounted on the apparatus main body. The process cartridge according to claim 1, wherein: Furthermore, the process cartridge includes:
The process cartridge according to claim 1, further comprising a tension pulley that applies tension to the drive transmission belt.   4. The process cartridge according to claim 1, wherein the drive transmission belt is a double-sided toothed belt, and the plurality of pulleys are toothed pulleys that mesh with the drive transmission belt. In an electrophotographic image forming apparatus in which a process cartridge is detachably attached to an image forming apparatus main body and an image is formed on a recording medium.
(I) main body driving means;
(Ii) a transfer roller for transferring the developed image to the recording medium;
(Iii) a transfer roller pulley for driving the transfer roller;
(Iv) an electrophotographic photosensitive member, a developing unit that develops a latent image formed on the electrophotographic photosensitive member with a developer, and a drive that is connected to the main body driving unit and transmits a driving force to the electrophotographic photosensitive member. A receiving portion, a photosensitive pulley driven by the driving force received by the electrophotographic photosensitive member from the driving receiving portion, and a drive transmission belt engaged with the photosensitive pulley, wherein the process cartridge is the device A mounting means for detachably mounting a process cartridge having a drive transmission belt that engages with the transfer roller pulley to increase a winding angle between the photosensitive pulley and the drive transmission belt when mounted on a main body;
(V) conveying means for conveying the recording medium;
An electrophotographic image forming apparatus comprising:   The transfer roller pulley is provided with a movable pulley that is movably provided to the process cartridge by engaging with the transfer roller pulley when the process cartridge is mounted on the apparatus body. The electrophotographic image forming apparatus according to claim 5, wherein the electrophotographic image forming apparatus is moved in a direction in which the winding angle is increased.   The electrophotographic image forming apparatus according to claim 5, wherein the transfer roller pulley is engaged with the drive transmission belt on an upstream side in the mounting direction of the process cartridge.   The electrophotographic image forming apparatus according to claim 5, wherein the transfer roller pulley is engaged with the drive transmission belt on a downstream side in the mounting direction of the process cartridge.   The electrophotographic image forming apparatus according to claim 5, wherein the transfer roller pulley is coaxial with the transfer roller.   The electrophotographic image forming apparatus according to claim 6, wherein the electrophotographic image forming apparatus includes a restricting portion that restricts movement of the movable pulley, and the restricting portion is coaxial with the transfer roller pulley.   The electrophotographic image forming apparatus according to claim 5, wherein the transfer roller pulley is a toothed pulley.

Images